There is a free service at: http://www.hoaxkill.com/
Where they say:
I received a hoax message, now what?
Whatever you do, don't send it to all your friends. Most of these messages have been forwarded dozens of times and contain a huge number of addresses of people who have received this message before you. If you have enough time you could extract all the addresses by hand and warn all these people about the nature of this message.
Alternatively, you could forward the message to hoaxkill@hoaxkill.com. The HoaxKill program will automatically extract all addresses from the message and send warnings to all the people who have received the hoax message. Please note that we keep a list of all the people we've warned so they will only receive one warning.
Virus Hoaxes and Chain Letters
Our network has received a large number of email messages concerning virus hoaxes and chain letters. A list of the more common "Virus Hoaxes" that have circulated are listed below. These messages typically have the following words in the content of the message or in the subject line of the message:
A list of the more common "Chain Letters" are listed below. These messages typically have the following words in the content of the message or in the subject line of the message:
If you receive e-mail messages about a virus or a message that encourages you to forward the information in the message to others, please don't. The propagation of these types of messages can significantly slow down the network, denying an expected level of service for legitimate uses. We recommend that anyone who receives an e-mail message claiming to contain a virus or a message that contains information about a suspected virus take the following steps:
Items listed above as either "Virus Hoaxes" or "Chain Letters" should be deleted.
Further information and current listings: